Plantar Flexor Research Articles

Low intensity, high frequency vibration training to improve musculoskeletal function in a mouse model of volumetric muscle loss.

This study's objective was to investigate the extent to which two different levels of low-intensity vibration training (0.6 g or 1.0 g) affected musculoskeletal structure and function after a volumetric muscle loss (VML) injury in male C57BL/6J mice. All mice received a unilateral VML injury to the posterior plantar flexors. Mice were randomized into a control group (no vibration; VML-noTX), or one of two experimental groups. The two experimental groups received vibration training for 15-min/day, 5-days/week for 8 weeks at either 0.6 g (VML-0.6 g) or 1.0 g (VML-1.0 g) beginning 3-days after induction of VML. Muscles were analyzed for contractile and metabolic adaptations. Tibial bone mechanical properties and geometric structure were assessed by a three-point bending test and microcomputed tomography (µCT). Body mass-normalized peak isometric-torque was 18% less in VML-0.6 g mice compared with VML-noTx mice (p = 0.030). There were no statistically significant differences of vibration intervention on contractile power or muscle oxygen consumption (p ≥ 0.191). Bone ultimate load, but not stiffness, was ~16% greater in tibias of VML-1.0 g mice compared with those from VML-noTx mice (p = 0.048). Cortical bone volume was ~12% greater in tibias of both vibration groups compared with VML-noTx mice (p = 0.003). Importantly, cross-section moment of inertia, the primary determinant of bone ultimate load, was 44% larger in tibias of VML-0.6 g mice compared with VML-noTx mice (p = 0.006). These changes indicate that following VML, bones are more responsive to the selected vibration training parameters than muscle. Vibration training represents a possible adjuvant intervention to address bone deficits following VML.

Chronic effects of a static stretching intervention program on range of motion and tissue hardness in older adults

IntroductionClinically, knowing whether a static stretching (SS) intervention program conducted for several weeks can reduce passive muscle stiffness is important. Still, only a few previous studies have evaluated the chronic effects of an SS intervention program in older adults, and the potential relationship between ROM changes and muscle stiffness changes is still unclear. This study aimed to investigate the effects of a 10- week SS intervention partially supervised program on joint range of motion (ROM) and tissue hardness in older adults.MethodsThe SS intervention program was conducted at least three times a week for 10 weeks in the ankle plantar flexor muscles of 24 community-dwelling older adults (73.8 ± 5.1 years; height: 156.0 ± 6.8 cm; body mass: 52.7 ± 8.0 kg). The SS intervention program consisted of 4 × 30-s repetitions. Ankle joint dorsiflexion (DF) ROM and tissue hardness of the medial gastrocnemius were measured before and after the 10-week SS intervention program.Results and discussionThe results showed that the 10-week SS intervention program significantly increased DF ROM (+9°, p < 0.01, Cohen’s d = 1.37) and decreased tissue hardness (−0.9, p = 0.04, Cohen’s d = −0.27). However, there was no significant correlation between these changes (r = 0.086, p = 0.561). The results of this study suggest that a 10-week SS intervention program can effectively increase DF ROM and decrease tissue hardness but that the increase in DF ROM is related to stretch tolerance rather than changes in tissue hardness.

Neuromuscular fatigability is not affected by the contraction pattern of exercises with a similar mean torque

Neuromuscular fatigability is not affected by the contraction pattern of exercises with a similar mean torque

Effectiveness of Ankle-Foot Orthoses for Patients with Weakness of the Plantarflexors and Dorsiflexors: Biomechanical Comparison of Different Orthotic Concepts

Abstract Introduction Weakness of plantarflexor and dorsiflexor muscles is a complex individual condition and can result in pathological gait, such as crouch gait or knee hyperextension. Affected patients can be supported with ankle-foot orthoses (AFOs) to improve gait and safety. Objective This study aims to compare three orthotic ankle joint designs in AFOs for patients with muscle weakness in the plantarflexors and/or dorsiflexors: a conventional hinged ankle joint with rigid stops (CAJ), a jointless orthosis (JLO), and a reactive-dynamic ankle joint with adjustable spring modules (RDA). Study Design Seven patients with plantarflexor and/or dorsiflexor muscle weakness tested three orthosis configurations in randomized order during a single session. Methods Biomechanical gait analysis was performed during standing and walking on level ground and up and down 10° slopes. The main outcomes were ground reaction forces, joint angles, moments, and power at the ankle, knee, and hip joints. Mean values of outcome measures for patients and values of an able-bodied control group were compared with nonparametric analyses of variance and pairwise post hoc tests. Results Throughout all motion tasks, statistically significant differences (P < 0.05) were predominantly found in ankle and knee joint kinematics between RDA and CAJ, as well as between JLO and CAJ, whereas only few differences were found between RDA and JLO. Conclusions For this patient group, RDA enabled the most physiological gait, with outcomes measure values closest to those of the able-bodied control group, and the best perception of support for an active lifestyle and physically demanding activities. In less physically demanding situations, such as short walking distances and even surfaces, JLO also showed sufficient support for physiological gait and may be an adequate orthosis for patients living with supportive infrastructure or a more sedentary lifestyle. CAJ restricted physiological movements, showed the highest deviations from the values of the able-bodied controls in most activities, and provides the least comfort for patients in the tested situations. Clinical Relevance Statement Determining the best possible orthotic care and support for different patient groups is essential to enable independence, safety, and comfort during activities of daily living based on individual requirements.

Effect of selective dorsal rhizotomy on neuromuscular symptoms, muscle morphology, and motor function in children with spastic cerebral palsy.

To investigate the effect of selective dorsal rhizotomy (SDR) on an integrated outcome set 1-year post-SDR, in a cohort of children with spastic cerebral palsy (CP). Fifteen children with bilateral spastic CP (median age 8 years 8 months [interquartile range 3 years 3 months], 11 males, four females, eight in Gross Motor Function Classification System (GMFCS) level II, seven in GMFCS level III) were measured pre- and 1-year post-SDR. Clinical scales and goniometry assessed plantar flexor spasticity, range of motion, strength, and selectivity. Spasticity was also quantified via an instrumented assessment. Medial gastrocnemius macroscopic muscle morphology (absolute and normalized muscle belly, tendon and muscle-tendon unit length, cross-sectional area, muscle volume) was assessed using ultrasound. Gait profile score, ankle and knee gait variable scores, walking speed, cadence, and step length were extracted from gait analysis. Gross motor function was assessed using the Gross Motor Function Measure-66 item set. Wilcoxon signed-rank test was used to analyse pre- and post-SDR changes. A reference database was used to qualitatively judge muscle growth post-SDR with respect to muscle growth of children with spastic CP without SDR intervention. Significant changes (p < 0.05) were seen for spasticity, selectivity, all absolute morphology parameters, normalized tendon and muscle-tendon unit length, and all gait parameters, except walking speed and cadence. Muscle growth of children with and without SDR was comparable. SDR is an effective spasticity reducing treatment and does not adversely affect natural muscle growth in spastic CP.

Decreased Knee Extensor Torque During Single-Limb Stance: A Computer Simulation Study of Compensations and Consequences

Background/Objectives: For over 50 years, it has been suggested that the plantar flexors and hip extensors can compensate for weak knee extensors and prevent collapse of the leg during a single-limb stance. However, the effects of these compensations have not been studied thoroughly. The purpose of this computer simulation study was to determine, for a given posture, the hip and ankle net joint torque (NJT) required to prevent leg collapse due to systematic decreases in knee NJT and to determine the effect of these compensations on the horizontal ground reaction force. Methods: Single-limb stance was simulated using a static, multisegmented model in eight different postures. For each posture, the knee NJT was systematically decreased. The ankle and knee NJT necessary to prevent lower extremity collapse, along with any net horizontal ground reaction forces, were then calculated. Results: Decreases in knee NJT required linear increases in ankle and hip NJT to prevent the limb from collapsing. There were greater increases in ankle NJT compared to hip NJT, resulting in posteriorly-directed horizontal ground reaction forces. While the magnitudes were different, these findings applied to all postures simulated. Conclusions: For a given posture, ankle and hip NJTs can compensate for a decrease in knee NJT. However, this resulted in a horizontal ground reaction force, which was in the posterior direction for all the postures examined. This horizontal ground reaction force would induce an acceleration on the body’s center of mass that, if not accounted for, could have deleterious effects on achieving a task objective.

Machine Learning Model for Predicting Walking Ability in Lower Limb Amputees.

Background/Objectives: The number of individuals with lower limb loss (LLL) is rising. Therefore, identifying the walking potential in individuals with LLL and prescribing adequate prosthetic systems are crucial. Various factors can influence participants' walking ability, to different extents. The aim of the present study was to apply machine learning methods to develop a predictive mode. This model can assist rehabilitation and limb loss care teams in making informed decisions regarding prosthesis prescription and predicting walking ability in individuals with LLL. Methods: The present study was designed as a prospective cross-sectional study encompassing 104 consecutively recruited participants with LLL (average age 62.1 ± 10.9 years, 80 (76.9%) men) at the Medical Rehabilitation Clinic. Demographic, physical, psychological, and social status data of patients were collected at the beginning of the rehabilitation program. At the end of the treatment, K-level estimation of functional ability, a Timed Up and Go Test (TUG), and a Two-Minute Walking Test (TMWT) were performed. Support vector machines (SVM) were used to develop the prediction model. Results: Three decision trees were created, one for each output, as follows: K-level, TUG, and TMWT. For all three outputs, there were eight significant predictors (balance, body mass index, age, Beck depression inventory, amputation level, muscle strength of the residual extremity hip extensors, intact extremity (IE) plantar flexors, and IE hip extensors). For the K-level, the ninth predictor was The Multidimensional Scale of Perceived Social Support (MSPSS). Conclusions: Using the SVM model, we can predict the K-level, TUG, and TMWT with high accuracy. These clinical assessments could be incorporated into routine clinical practice to guide clinicians and inform patients of their potential level of ambulation.

Reliability of isokinetic dynamometer for isometric assessment of ankle plantar flexor strength

ObjectiveTo evaluate isokinetic dynamometer reliability for isometric assessment of plantar flexor (PF) strength. DesignCross-sectional. SettingTesting by the same physiotherapist twice during a first session (repeatability) and once during a second session (reproducibility). ParticipantsTwenty-two healthy subjects (44 ankles, 11 men/11 women). Main outcome measuresIsometric PF peak torque, with and without body mass normalization, at 0° and +20° of plantar flexion. Measurement reliability was evaluated using intraclass correlation coefficient (ICC), standard error of measurement (SEM) and minimal detectable change (MDC). ResultsWithout normalization, measurement repeatability was excellent at 0° of plantar flexion (ICC, 0.94; SEM, 6.6%; MDC, 18.4%) compared with good repeatability at +20° (ICC, 0.85; SEM, 11.1%; MDC 30.6%). Measurement repeatability following normalization was good at 0° (ICC, 0.88; SEM, 5.2%; MDC, 14.4%) and +20° (ICC, 0.79; SEM, 10.2%; MDC, 28.1%). While reproducibility was good at 0° with normalization (ICC, 0.84; SEM, 5.9%; MDC, 16.3%) or excellent without (ICC 0.92; SEM 7.5%; MDC, 20.8%), it was moderate at +20° with normalization (ICC 0.71; SEM 11.3%; MDC, 31.3%) or good without (ICC 0.78; SEM 13.0%; MDC, 36.1%). ConclusionThe reliability of PF maximal isometric strength is good/excellent at 0° of plantar flexion but moderate/good at +20°.

Effect of Footwear Longitudinal Bending Stiffness on Energy Cost, Biomechanics, and Fatigue During a Treadmill Half-Marathon.

Introduction: Carbon plates have been used to increase running shoes' longitudinal bending stiffness (LBS), but their effect during a long duration run remains unknown. Our study aimed to identify the effect of LBS on energy cost of running (Cr), biomechanics, and fatigue during a half-marathon.Methods: Thirteen well-trained male runners (half-marathon time < 1 h40) performed two half-marathons at 95% of the running speed associated with their second ventilatory threshold on two separate visits, with either high-LBS shoes (HLBS, with carbon-plates) or standard-LBS (SLBS) shoes. Before and after the half-marathon, Cr at 12 km/h with both shoes (two 6-min bouts: Cr12) and ankle plantarflexors (PF) force were measured. During the half-marathon, running kinematics, shoe perceived comfort, and Cr were assessed.Results: During Cr12 measurements before and after the half-marathon, HLBS was 1.0 ± 2.1% more economical than SLBS (p < 0.001). During the half-marathon, Cr increased with running duration (p = 0.048) but there was no distance × condition effect. HLBS increased contact time (+3%, p = 0.01), decreased metatarsophalangeal joint dorsiflexion (-9%, p = 0.01), and was perceived less comfortable than SLBS, independently from running duration. At the end of the half-marathon, HLBS shoes led to higher PF force loss (-20.0 ± 9.8% vs -13.3 ± 11.0%, p = 0.048).Conclusions: Adding curved carbon plates in the running shoes slightly improved Cr during short running bouts at low intensity but not during a half-marathon. This discrepancy may be explained by day-to-day Cr variability and variation in shoe comfort. PF fatigue was higher with HLBS shoes but the accentuated fatigue did not further impact the biomechanical perturbations induced by the plates. Our results suggest that carbon plates alone do not provide a significant advantage for half-marathon performance.

Plantar flexor strength and size decrease following single-leg disuse in uninjured adults: A meta-analysis.

Plantar flexors play a pivotal role in human locomotion and balance. Several original research studies and systematic reviews have characterised the impact of single-leg disuse on plantar flexor strength and size. However, no meta-analysis has quantified the effects of single-leg disuse on changes in plantar flexor strength and size in uninjured adults. To quantify changes in plantar flexor strength and size in response to single-leg disuse. Data were extracted from 19 studies captured in our previous systematic review on studies that employed a unilateral lower limb immobilisation model (cast or brace) and were published up to January 30, 2022. Random-effects meta-analyses were performed on original research studies reporting measures of plantar flexor strength (isometric, isokinetic, or repetition maximum) and size (magnetic resonance imaging or computed tomography) in uninjured adults. Single-leg disuse decreased plantar flexor strength (Hedges gav = -0.71 [95% confidence interval: -0.93, -0.48], p < 0.001, 7-28 days, N = 16 studies, n = 121 participants including ≥13 females, ages 19-29) and plantar flexor size (-0.33 [-0.50, -0.15], p < 0.001, 14-35 days, N = 6, n = 49, 10 females, ages 22-27) across all durations of disuse. Single-leg disuse decreases plantar flexor strength and size in uninjured adults. This work adds to recent meta-analytic findings demonstrating the declines in knee extensors strength and size following single-leg disuse. The paucity of female and participants >30 years old in the single-leg disuse literature examining plantar flexors represents a priority of future work.

Effects of knee joint position on the triceps Suræ torque-size relationship during plantarflexion in healthy young adults

We determined the effects of knee joint position on the relationship between maximal voluntary contraction (MVC) isometric plantar flexor torque and architectural properties of the plantar flexors measured at rest in healthy young adults. We obtained 3-D reconstructed muscle architecture data of the right plantar flexor muscles of nine physically active males using T1 and DTI MRI sequences with the knee in ∼5° flexion and at rest. Muscle volume, fascicle length, pennation angle, and physiological cross-sectional area were estimated for the medial and lateral gastrocnemius and the soleus muscle. MVC isometric plantar flexor torque was assessed on a dynamometer with the knee flexed and extended. MVC isometric plantar flexor torque was 59 % lower when performed with the knee flexed (93.1 ± 22.3 N∙m) vs. extended (154.4 ± 37.8 N∙m). Medial (r = 0.70, p = 0.026) and lateral gastrocnemius (r = 0.49, p = 0.048), total soleus (r = 0.79, p = 0.01), and total triceps suræ muscle volume (r = 0.77, p = 0.012) correlated with MVC isometric plantarflexion torque produced with the knee extended. However, only total soleus (r = 0.64, p = 0.028) and triceps suræ volume (r = 0.64, p = 0.031) correlated with MVC isometric plantar flexor torque produced with the knee flexed. Only the total soleus (r = 0.66, p = 0.038) and triceps suræ physiological cross-sectional area (r = 0.55, p = 0.049) correlated with MVC isometric plantar flexor torque performed with knee extended. The data suggest that knee joint position affects torque-size relationship in the gastrocnemius muscles. Additionally, it appears that the total soleus and triceps suræ muscle volumes association with MVC isometric plantar flexor torque is larger than the total physiological cross-sectional area of the triceps suræ. In conclusion, the data suggest that knee joint position affects torque-size relationship in the gastrocnemii but not in the soleus muscle.

Do Plantar-Flexor Muscle Structure and Function Contribute to Medial Tibial Stress Syndrome in Long-Distance Runners? A Case Report.

Two long-distance runners developed medial tibial stress syndrome (MTSS; male age = 26.3 years, female age = 47.5 years) after baseline assessment of plantar-flexor muscle structure and function and spatiotemporal running variables. B-mode ultrasound and lean leg girth characterized plantar-flexor muscle structure. Handheld dynamometry and a single-leg heel raise-to-failure protocol characterized plantar-flexor muscle function. Finally, spatiotemporal running variables were determined during a treadmill protocol. The 2 runners who developed MTSS demonstrated less plantar-flexor strength and endurance capacity than published comparative control data and marked variability in muscle structure. Reduced plantar-flexor strength and endurance capacity were thought to contribute to an impaired ability to resist tibial-bending moments during midstance due to earlier muscle fatigue. Earlier muscle fatigue could, in turn, contribute to increased tibial-bending moments and MTSS development. Therefore, assessing plantar-flexor muscle strength and endurance might help to identify athletes at risk of developing MTSS.

Impact of eccentric cycling in coronary rehabilitation program: a pragmatic randomized controlled trial versus conventional rehabilitation.

This randomized controlled trial examined the feasibility of adding eccentric exercise to a conventional cardiac rehabilitation program (CCRP) for coronary heart disease patients. Ninety-three patients were randomly assigned to either the MIX group (eccentric ergometer + CCRP) or the CON group (concentric ergometer + CCRP) for 7 weeks. Training effectiveness was assessed based on "good responders" showing improved functional capacities, such as 6-minute walk test (6MWT) distance and maximal voluntary contraction of the plantar flexors (ankle MVC). Safety was monitored with a visual analog scale for muscle soreness, perceived exertion, and heart rate during training. The proportion of good responders was similar between groups (26% in MIX, 29% in CON, P=0.744). Both groups improved in 6MWT (CON: 12.6%, MIX: 16.14%) and ankle MVC (CON: 15.5%, MIX: 11.30%), with no significant differences. Exercise tolerance did not differ significantly between the groups, but perceived effort was significantly lower in the MIX group (P<0.0001) compared to the CON group. Integrating eccentric exercise into cardiac rehabilitation is safe and well-tolerated. Nevertheless, this study did not find significant advantages over conventional programs for coronary heart disease patients. Further research should explore specific patient groups or conditions where eccentric exercise may be more beneficial, emphasizing personalized prescriptions and gradual workload progression for better cardiac rehabilitation outcomes.

Effects of Supervised Exercise Therapy on Muscle Function During Walking in Patients with Peripheral Artery Disease.

Although supervised exercise therapy (SET) is a primary treatment for peripheral artery disease (PAD), the current literature is limited regarding the mechanisms contributing to increased walking distances, including how lower extremity muscle function is altered after SET. This study aimed to investigate the effects of SET on lower extremity muscle function during walking in patients with PAD. Twelve patients with PAD participated in a 6-month SET program consisting of three weekly exercise sessions (a total of 72 sessions) and adhered to the American College of Sports Medicine's (ACSM) recommendations. Each session started with a 5 min warm-up of mild walking and static stretching of upper and lower body muscles, followed by 50 min of intermitted exercise on a treadmill, and then finished with 5 min of cool-down activities similar to the warm-up. Each patient walked across a 10 m pathway with reflective markers on their lower limbs twice: before (baseline) and after six months of participation in SET (post-exercise). Marker coordinates and ground reaction forces were recorded and imported to OpenSim software (version 4.0) for gait simulations. Muscle force, muscle power, and metabolic rate were estimated from OpenSim and compared between the baseline and post-exercise. The mean plantar flexor force was not altered after SET. However, individuals' plantar flexor muscles demonstrated improvements in force production (lateral gastrocnemius: 75-80% of stance, Cohen's d = 0.20-0.43; medial gastrocnemius: 65-85% of stance, Cohen's d = 0.20-0.71; soleus: 90-95% of stance, Cohen's d = 0.20-0.26). Furthermore, plantar flexor power increased (80-95% of stance, Cohen's d = 0.20-0.39) and this was attributed to increased power in the lateral gastrocnemius (80-85% of stance, Cohen's d = 0.20-0.47), medial gastrocnemius (80-90% of stance, Cohen's d = 0.22-0.60), and soleus muscles (85-95% of stance, Cohen's d = 0.20-0.49). Similarly, other muscle groups (knee extensors, knee flexors, hip abductors, hip adductors, hip extensors, and hip flexors) also exhibited force and power increases after SET. Additionally, force and power variances were significantly decreased in several muscle groups (plantar flexors, knee extensors, hip abductors, hip external rotators, hip extensors, and hip flexors). Total metabolic rate also increased during the stance period where muscle force and power were elevated after SET (early stance: 5-25%, Cohen's d = 0.20-0.82; mid stance: 35-45%, Cohen's d = 0.20-0.47; late stance: 75-80%, Cohen's d = 0.20-0.36). Our results suggest that from a biomechanics perspective, muscle functions during walking are improved in patients with PAD after SET; however, the improvements were generally small and were not reflected by all muscle groups.

Muscle characteristics of lower limb in association with physical activity in candidates of total knee arthroplasty with knee osteoarthritis

Background&AimsThis study aimed to clarify the association between physical activity (PA) and physical functions, including both muscle quantity and quality of ankle plantar flexor muscles in patients with knee osteoarthritis (OA). MethodsA retrospective cohort study was conducted with ninety-two patients with knee OA. PA, leg muscle cross-sectional area (CSA), knee strength, passive knee angle, and knee pain of the affected side were assessed. PA was assessed by the 2011 Knee Society scoring system. CSA of the quadriceps and ankle plantar flexor muscles on the affected side was measured using a computed tomography image. Based on muscle attenuation assessed with Hounsfield units (HU), the muscle quality of targeted muscle was divided into 4 groups as follows: fat tissue (-190 to -30 HU), very low-density muscle (-29 to -1 HU), low-density muscle (0 to 34 HU), and normal-density muscle (NDM, 35 to 100 HU). The CSA was obtained for each of the 4 groups. Univariate and multivariate linear regression analyses were performed to determine the factors associated with PA. ResultsThe regression analysis revealed that higher PA was independently associated with the NDM CSA of ankle plantar flexor (β = 0.51), higher knee extension strength (β = 0.28), and milder knee pain (β = -0.29) after adjustment with age, sex, height, weight, and body mass index. ConclusionThe present study suggested that NDM CSA of ankle plantar flexor in addition to knee function is one of the factors determining the PA in patients with knee OA.

Reliability of a standardized protocol of the Single Leg Heel Rise Test

The single leg heel rise (SLHR) test is a widely used method for assessing calf muscle-tendon unit (MTU) endurance in various fields, including medicine, sports, and dance. The objectives of this study were to examine the reliability of a standardized SLHR test protocol with a heel rise measurement device and to investigate the relationship between SLHR repetitions, SLHR total work, and both maximal voluntary isometric contraction (MVIC) and reactive strength index (RSI) outcomes of the plantar flexors. 21 sport students (8 females, 13 males) were assessed for SLHR outcomes (number of repetitions, height of heel rises, total positive work performed) in two data collection sessions, as well as unilateral lower extremity MVIC and RSI. Test-retest reliability showed excellent reliability and low variability for the number of repetitions (Intraclass correlation coefficient (ICC)=0.91, 95% CI: 0.73 to 0.97; coefficient of variability (CV): 8.1- 8.7%), height of the heel rises (ICC=0.92, 95% CI: 0.81 to 0.97; CV: 4.6 - 5.2%) and total positive work performed (ICC=0.96, 95% CI: 0.87 to 0.99; CV: 6.8 - 9.8%) in both feet. No significant correlation was identified between SLHR repetitions, MVIC, and reactive strength outcome measures. A moderate correlation was observed between the total work performed in the SLHR and RSI outcomes that could potentially be explained by the body weight (BW) of the participants. The SLHR test provides reliable measures for lower leg muscular endurance, yet it does not predict plantar flexor maximal strength or reactive strength. In future studies, we advise employing this standardized protocol for screenings of athletes and dancers.

Investigating the Effect of Nintendo Wii Games on Clinical and Neural Properties of Ankle Spasticity in Patients with Stroke: A Randomized Clinical Trial

Background: Stroke is one of the most common causes of disability. Spasticity is a common clinical impairment that occurs after a stroke. Spasticity occurs due to changes in the mechanical properties of the muscle and the neural properties following a stroke. Objectives: This study aimed to investigate the effect of Nintendo Wii games on ankle spasticity outcomes in stroke patients. Methods: In this parallel single-blind clinical trial study, 30 patients with stroke were randomly assigned to one of the experimental and control groups. The subjects of both groups received conventional physiotherapy, including stretching of ankle plantar flexor muscles and walking exercises on parallel bars. In addition, the experimental group also received Nintendo Wii games for 30 minutes three times a week for a total of 12 sessions. Clinical outcomes of spasticity and neural properties were evaluated using the Modified Ashworth Scale and H-reflex latency and Hmax/Mmax ratio. All statistical analyses were performed using SPSS version 20. Results: The intragroup results showed that the clinical outcome of spasticity was significantly reduced in the experimental group (P = 0.001). The comparison between the two groups showed no statistically significant difference in clinical outcome and neural properties between the experimental and control groups (P &gt; 0.05). Conclusions: Based on the results, the clinical outcome of spasticity was significantly reduced after the end of the treatment in the Nintendo Wii group. The use of Nintendo Wii can be suggested as a treatment modality alongside the usual treatments to achieve greater and faster effectiveness in patients with stroke.

Associations Between Inter-Limb Asymmetry in Lower Limb Strength and Jump Performance in 14–15-Year-Old Basketball Players

This study aims to (1) assess the inter-limb asymmetry in hip, knee, and ankle strength and countermovement jump (CMJ) performance among adolescent basketball players and (2) examine the relationship between inter-limb asymmetry and CMJ performance. Moreover, 30 adolescent basketball players (15 boys and 15 girls) aged 14 to 15 years participated in this study. The strength of the lower limb joints was measured using an isokinetic dynamometer at a speed of 60 degrees per second. Three maximal CMJs were performed, and the highest jump was used for the final analysis. The subjects were median-split into high-asymmetry (n = 15) and low-asymmetry (n = 15) groups based on the calculated strength asymmetry scores. The asymmetry scores were calculated using the formula: (dominant–non-dominant)/dominant* 100%. The inter-limb asymmetry data ranged from 12.2% to 21.6%. A Spearman correlation analysis showed that only the inter-limb asymmetry of the ankle plantar flexor was significantly correlated with the CMJ heights (ρ = −0.56, p = 0.001). An independent t-test revealed no significant differences in strength asymmetry between boys and girls (all p &gt; 0.05). The low-asymmetry group demonstrated significantly greater CMJ performance compared to the high-asymmetry group (ES = 1.11, 95% CI = 0.34–1.87, p = 0.007), indicating that inter-limb asymmetry of the ankle plantar flexor has a significant negative impact on CMJ performance. Coaches should focus on enhancing both the strength and symmetry of the ankle joints to improve athletic performance and prevent injuries in sports, where jumping is a common movement.

Centrally mediated responses to NMES are influenced by muscle group and stimulation parameters

Wide-pulse high-frequency neuromuscular electrical stimulation (WPHF NMES) can generate a progressive increase in tetanic force through reflexive recruitment of motor units, called extra force. This phenomenon has previously been observed on different muscle groups, but little is known on potential inter-muscle differences. We compared extra force and sustained electromyographic (EMG) activity induced by NMES between plantar flexors, knee extensors, elbow flexors and within muscle groups using pulse durations of 0.2, 1 and 2 ms and stimulation frequencies of 20, 50, 100 and 147 Hz. Extra force production and sustained EMG activity were higher for plantar flexors compared to elbow flexors at all tested parameters (except 0.2 ms for extra force). When compared to elbow flexors, extra force of the knee extensors was only higher at 100 Hz and with 1 ms while sustained EMG activity was higher at all frequencies with pulse durations of 0.2 and 2 ms. Peripheral nerve architecture as well as muscle typology and function could influence the occurrence and magnitude of centrally-mediated responses to NMES. The present findings suggest that the use of wide-pulse high-frequency NMES to promote reflexive recruitment seems to be more pertinent for lower limb muscles, plantar flexors in particular.

Effects of Maturation on Plantar Flexor Activity and Achilles Tendon Stiffness in Vertical Jumping: Sex Differences.

The aim of this study was to investigate the effect of maturation on vertical jumping performance, in adolescent boys and girls, concerning plantar flexor activity and Achilles tendon (AT) stiffness. Thirty-nine adolescents were tested in a counter-movement jump (CMJ) at three different time points: 18 and 9 months before peak height velocity (PHV) and at PHV. The EMG activity of the medialis gastrocnemius (MG) and tibialis anterior (TA) muscles was evaluated, in relation to jump height. Boys showed higher jumping ability and AT stiffness than girls. Additionally, boys revealed increased eccentric (ecc) and concentric (con) MG activity, along with decreased ecc and con TA activity, near PHV. On the other hand, girls showed increased ecc and con TA/MG co-contraction compared to boys, mainly near PHV. In conclusion, a different mechanism of vertical jumping performance is adopted between early adolescent boys and girls. Nevertheless, no notable alterations in jumping capability were detected over time, indicating that the maturation process does not influence stretch-shortening cycle (SSC) performance.